code: def _handle_modulation(events):
      """Set the modulation column to 1 if it is not present."""
      if "modulation" in events.columns:
          print(
              "A 'modulation' column was found in "
              "the given events data and is used."
          )
      else:
          events["modulation"] = 1
      return events
  
file_path: nilearn/nilearn/glm/first_level/experimental_paradigm.py
imports: import warnings
  import pandas
  from pandas.api.types import is_numeric_dtype
label_desc: Use image node_id 5 for calling a global function with example usage: _handle_modulation(events) and returns: events